Modified MT ferrule with removed cantilevered fibers and internal lenses and mold pin

ABSTRACT

A modified MT fiber optic ferrule has optical fiber receiving holes by the front end to receive the ends of optical fibers inserted into and through the ferrule. The optical fiber receiving holes are aligned with optical fiber openings in the center of the ferrule and have lenses formed in the optical fiber receiving holes to collimate from or focus light into the optical fibers in the fiber optic ferrules. The front end of the fiber optic ferrule may also have integral mating surfaces.

REFERENCE TO RELATED CASE

This application claims priority under 35 U.S.C. § 119 (e) toprovisional application No. 61/939,508 filed on Feb. 13, 2014, thecontent of which is hereby incorporated by reference in its entirety.

BACKGROUND OF THE INVENTION Field of the Invention

Optical fiber ferrules are typically mated to another ferrule in alarger system to mate the light traveling down optical fibers. The lightexiting an optical fiber tends to diverge. As a result, some fiber opticferrules have lenses on the front face to collimate the diverging lightas it exits from the optical fibers. The mating fiber optic ferrule,also having lenses, causes the collimated light to be focused into theoptical fibers disposed in the mating fiber optic ferrule. However, thealignment of the optical fibers with the lenses in the ferrules iscritical to maintain a low insertion loss between the two fiber opticferrules. Typically, the optical fibers are inserted until they engage aoptical fiber stop plane. However, even with the most cautious insertiontechniques, the optical fibers may deflect or even bend within the fiberoptic ferrule. If the tips of the optical fibers are bent, then theexiting light may not be adequately collimated by the lenses (or focusedby the lenses in the mated fiber optic ferrule), causing a highinsertion loss.

Thus, an fiber optic ferrule is needed that allows for the opticalfibers inserted into the fiber optic ferrule to be aligned with lensesin an easy and straightforward manner.

SUMMARY OF THE INVENTION

The present invention is directed to fiber optic ferrule that includes amain body having a front end, a back end, and a middle portion disposedbetween the front end and back end, a first opening through the back endof the main body, the first opening configured to receive at least twooptical fibers through the back end of the main body, a plurality ofoptical fiber openings disposed in the middle portion and incommunication with and extending from the first opening toward the frontend, each of the plurality of optical fiber openings configured toreceive an optical fiber inserted through the back end, a second openingdisposed between the middle portion and the front end, the secondopening extending through a surface of the main body perpendicular to afront face disposed at the front end of the main body, and a frontportion, the front portion disposed between the second opening and thefront end, the front portion having a plurality of optical fiberreceiving holes, each of the plurality of optical fiber receiving holescorresponding to one of the plurality of optical fiber openings in themiddle portion and opening into the second opening.

According to another aspect of the present invention, a fiber opticferrule is provided that includes a main body having a front end, a backend, and a middle portion disposed between the front end and back end, afirst opening through the back end of the main body, the first openingconfigured to receive at least one optical fiber through the back end ofthe main body, and at least one optical fiber opening in communicationwith and extending from the first opening toward the front end, the atleast one optical fiber opening configured to receive an optical fiberinserted through the back end, wherein the at least one optical fiberopening has a lens, the lens having a diameter that is equal to or smallthan a diameter of the at least one fiber opening.

In yet another aspect, a molding pin for use in molding a fiber opticferrule includes a main body having a proximal end and a distal end, andan end portion at the distal end, the end portion having a convexconfiguration for forming a lens in the fiber optic ferrule

Additional features and advantages of the invention will be set forth inthe detailed description which follows, and in part will be readilyapparent to those skilled in the art from that description or recognizedby practicing the invention as described herein, including the detaileddescription which follows, the claims, as well as the appended drawings.

It is to be understood that both the foregoing general description andthe following detailed description of the present embodiments of theinvention, and are intended to provide an overview or framework forunderstanding the nature and character of the invention as it isclaimed. The accompanying drawings are included to provide a furtherunderstanding of the invention, and are incorporated into and constitutea part of this specification. The drawings illustrate variousembodiments of the invention, and together with the description serve toexplain the principles and operations of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic of a cross section of a prior art ferrule;

FIG. 2 is a perspective view of one embodiment of a fiber optic ferruleaccording to the present invention;

FIG. 3 is a cross-sectional view of the fiber optic ferrule of FIG. 2:

FIG. 4 is an enlarged view of the front end of the fiber optic ferruleof FIG. 2;

FIG. 4A is an enlarged view of a portion of the front end of the fiberoptic ferrule in FIG. 3;

FIG. 4B is an enlarged view of the fiber optic ferrule in FIG. 3 withthree optical fibers inserted and disposed against a fiber stop and oneoptical fiber being inserted and illustrated before engaging the fiberstop;

FIG. 5 is an enlarged view of a front end of a fiber optic ferruleillustrating alternative mating surfaces;

FIG. 6 is an enlarged view of a front end of a fiber optic ferruleillustrating alternative mating surface with light transmission surfacesrecessed on a front face of the fiber optic ferrule;

FIG. 7 is a perspective view of one embodiment of a molding pin used tocreate an optical fiber opening in a fiber optic ferrule according tothe present invention;

FIG. 8 is an enlarged view of the distal end of the molding pin of FIG.7;

FIG. 9 is a cross-sectional view of the distal end of the molding pin ofFIG. 7;

FIG. 10 is a cross-sectional view of the distal end of an alternativeembodiment of a molding pin according to the present invention; and

FIG. 11 is a cross-sectional view of the distal end of a secondalternative embodiment of a molding pin according to the presentinvention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Reference will now be made in detail to the present preferredembodiment(s) of the invention, examples of which are illustrated in theaccompanying drawings. Whenever possible, the same reference numeralswill be used throughout the drawings to refer to the same or like parts.

Referring to FIG. 1 where a portion of a prior art fiber optic ferrule10 is illustrated. The fiber optic ferrule 10 has a middle portion witha plurality of optical fiber openings 12 that are in communication witha larger opening 14. The optical fibers 16 are inserted into theplurality of optical fiber openings 12 and pass through the largeropening 14 to the perpendicular surface 18. The perpendicular surface 18functions as a stop plane. While the optical fibers 16 may remainperfectly straight when they make contact with the perpendicular surface18, they may also bend as illustrated. If the optical fibers 16 bend,then the light is not directed at the lenses 20 that are on the frontface of the fiber optic ferrule 10. The plurality of optical fiberopenings 12 may also not be perfectly aligned with the lenses 20 duringthe molding of the fiber optic ferrule 10. As illustrated, the opticalfiber openings 12 may be formed an angle A relative to the center lineof the fiber optic ferrule and the axis of the lenses 20. The largeropening 14 has a distance C and B is offset of the optical fiber 16 asit exits from the optical fiber openings 12 and the focal point or thecenter of the ferrule and the lenses 20. The bending of the opticalfiber 16 due to improper insertion, debris, or shrinkage of the adhesiveduring curing is measure by D. As a result, the total offset of thefiber tip from the ideal location is B+C sin A+D.

Turning now to one embodiment of a fiber optic ferrule 50 according tothe present invention, the fiber optic ferrule 50 has a main body 52with a front end 54 and a back end 56 as illustrated in FIGS. 2-4B.Between the front end 54 and the back end 56 is a middle portion 58. Thefiber optic ferrule 50 has a first opening 60 through the back end 56 ofthe main body 52 to receive optical fibers 16. The fiber optic ferrule50 has a plurality of optical fiber openings 62 disposed within themiddle portion 58 of the main body 52. The plurality of optical fiberopenings 62 extend from the first opening 60 forward towards the frontend 54. The plurality of optical fiber openings 62 are configured toreceive the optical fibers fibers 16 inserted through the back end 56.The optical fibers 16 extend from the back end 56 through the middleportion 58 to an optical fiber stop 63. See FIGS. 4A and 4B. the opticalfiber stop 63 is a slight narrowing in each of the plurality of opticalfiber openings 62. This narrowing creates a shoulder that engages atleast a portion of an outer front face of the optical fibers 16. See,e.g., FIG. 4B. The optical fiber stop 63 is created by the shoulder 212in a molding pin, which is described in detail below and with referenceto FIG. 8. As a result of this configuration, the optical fibers 16 aresupported and secured by the plurality of optical fiber openings 62,thereby preventing any bending of the optical fibers 16 as illustratedin FIG. 1.

As illustrated in FIGS. 2 and 3, the plurality of optical fiber openings62 terminate at a second opening 64. The second opening 64 is configuredto receive an adhesive (preferably epoxy that has a refractive indexthat is different from that of the fiber optic ferrule 50) in order tosecure the optical fibers within the fiber optic ferrule 50. The secondopening 64 is illustrated as opening through a top surface 66 of thefiber optic ferrule 50. As would be known in the art, the second opening64 could be through another surface of the fiber optic ferrule 50 thatis perpendicular to the front face 68 of the fiber optic ferrule 50.

A front portion 70 is disposed between the second opening 64 in thefront end 54. In the front portion 70 are a plurality of lens holes 72.See FIG. 4. The lens holes 72 are in line with and are a continuation ofthe optical fiber openings 62. Typically, openings such as the lensholes 72 would be created using a second element, i.e., not the same pinthat is used to create the plurality of optical fiber openings 62.However, as noted below in detail, the same molding pin (molding pin200) is used to create both the optical fiber opening 62 and the lensholes 72. Using a single pin eliminates the stacking of tolerances forseparate elements and provides an accurate alignment of the opticalfiber opening 62 and the lens holes 72.

While a plurality of optical fiber openings 62 and the lens holes 72 areillustrated, it is possible to have fewer (or even more) openings andholes in a fiber optic ferrule than illustrate in the figures. Indeed,it would be possible to create such a optical fiber opening and theoptical fiber receiving hole in a single fiber ferrule.

As seen in FIGS. 4, 4A and 4B, the right side of the lens holes 72 has alens 76 formed in the fiber optic ferrule 50. The lens 76 is a convexlens that collimates the light exiting from the optical fibers 16disposed against the optical fiber stop 63 in the plurality of opticalfiber openings 62 and travels through the second opening 64 to thelenses 76. The position of the optical fiber stop 63 is based upon thefocal length of the lens 76, i.e., the distance from the optical fiberstop 63 to the lens 76 is the same as the focal length of the lens 76.The light then travels through the front portion 70 to the matingsurfaces 80 that are in optical alignment with the lens holes 72. Asillustrated in FIG. 4, the mating surfaces 80 extend beyond the frontface 68 of the fiber optic ferrule 50. When fiber optic ferrule 50 ismated with another fiber optic ferrule, the mating surfaces 80 wouldengage one another, thereby allowing the light to pass through thecorresponding lenses in the other fiber optic ferrule and be focusedonto and into the optical fiber. Since the mating surfaces 80 projectpast the front face 68 of the fiber optic ferrule 50, any air gapsbetween the two fiber optic ferrules will be eliminated. By eliminatingthe gaps between the fiber optic ferrules, fresnel losses will beeliminated. However, it should be noted that a fiber optic ferrule neednot have such mating surfaces at the front face 68 of the fiber opticferrule 50.

An alternative configuration for mating surfaces 80′ of fiber opticferrule 50′ is illustrated in FIG. 5. Rather than a flat engagingsurface on the mating surfaces 80 as illustrated in FIG. 4, the matingsurfaces 80′ may have a convex configuration as illustrated in FIG. 5.The convex configuration of mating surfaces 80′ would increase thedeformation of the ferrule mating surfaces, thereby eliminating any airgaps between the fiber optic ferrules.

FIG. 6 illustrates another configuration for the front face 68″ of afiber optic ferrule 50″. In this case, the mating surfaces become lighttransmission surfaces 80″ as the light transmission surfaces 80″ arerecessed below the front face 68″ of the fiber optic ferrule 50″.Instead of the transmission surfaces 80″ engaging one another in amating situation, an outwardly extending surface 82″ is used to engageother fiber optic ferrules.

A molding pin 200 used with a mold to make a fiber optic ferrule isillustrated in FIGS. 7-9. The molding pin 200 has a main body 202 with aproximal end 204 and a distal end 206. The length of the molding pin 200is as long as necessary given the fiber optic ferrule being molded.While the molding pin 200 can be of a single diameter, of a decreasingdiameter from the proximal end 204 to the distal end 206, or amulti-step diameter molding pin, a two-step diameter molding pin isillustrated. The first portion 208 adjacent the proximal end 204 has alarger diameter d1 than the second portion 210 with the diameter d2. Theshoulder 212 this position between the first portion 208 and the secondportion 210. The distal end 206 as an end portion 214 to form a lens inthe fiber optic ferrule. As illustrated in the figures, the end portion214 has a chamfered area 216 to assist in inserting the molding pin 200into the mold without skiving the mold. Radially inward from thechamfered area 216 is a concave portion 218 that forms the convex lensin the fiber optic ferrule.

In an alternative embodiment of a molding pin 200′, the end portion 214′does not have the chamfered area in the prior embodiment. Rather, theconcave portion 218′ extends radially outward to the edges of the secondportion 210′.

In yet another alternative embodiment of a molding pin 200″, the endportion 214″ has a flattened annular portion 216″ surrounding theconcave portion 218.

In all of these embodiments, it is important to note that the lensesformed by each of the molding pins would have a diameter that is lessthan the diameter of the second portion 210.

It will be apparent to those skilled in the art that variousmodifications and variations can be made to the present inventionwithout departing from the spirit and scope of the invention. Thus it isintended that the present invention cover the modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents.

I claim:
 1. A fiber optic ferrule comprising: a main body having a front end, a back end, and a middle portion disposed between the front end and back end; a first opening through the back end of the main body, the first opening configured to receive at least two optical fibers through the back end of the main body; a plurality of optical fiber openings disposed in the middle portion and in communication with and extending from the first opening toward the front end, each of the plurality of optical fiber openings configured to receive an optical fiber inserted through the back end and an optical fiber stop disposed within each of the plurality of optical fiber openings; a second opening disposed between the middle portion and the front end, the second opening extending through a surface of the main body perpendicular to a front face disposed at the front end of the main body; and a front portion, the front portion disposed between the second opening and the front end, the front portion having a plurality of lens holes, each of the plurality of lens holes corresponding to one of the plurality of optical fiber openings in the middle portion and opening into the second opening.
 2. The fiber optic ferrule according to claim 1, wherein each of the plurality of lens holes has a lens, the lens in each of the plurality of lens holes is disposed between the front face of the main body and the lens hole.
 3. The fiber optic ferrule according to claim 1, further comprising adhesive disposed in the second opening and the plurality of lens holes, the adhesive and the fiber optic ferrule having a refractive index that are different from one another.
 4. The fiber optic ferrule according to claim 1, the further comprising adhesive disposed in the second opening and the plurality of lens holes, the adhesive and the core of the optical fibers having a refractive index that are the same.
 5. The fiber optic ferrule according to claim 1, further comprising a plurality of mating surfaces disposed on the front face of the main body, each of the plurality of mating surfaces corresponding to one of the plurality of lens holes.
 6. The fiber optic ferrule according to claim 5, wherein the plurality of mating surfaces have a flat forward facing surface.
 7. The fiber optic ferrule according to claim 5, wherein the plurality of mating surfaces have a convex mating surface.
 8. The fiber optic ferrule according to claim 1, further comprising a mating surface, the mating surface corresponds to the front face of the fiber optic ferrule.
 9. The fiber optic ferrule according to claim 1, further comprising a plurality of light transmission surfaces, each of the plurality of light transmission surfaces being optically aligned with one of the plurality of lens holes and one of the plurality of optical fiber openings.
 10. The fiber optic ferrule according to claim 9, wherein the plurality of light transmission surfaces comprise a plurality of mating surfaces.
 11. The fiber optic ferrule according to claim 9, wherein the plurality of light transmission surfaces are recessed below a mating surface disposed on the front end of the main body.
 12. A fiber optic ferrule comprising: a main body having a front end, a back end, and a middle portion disposed between the front end and back end; a first opening through the back end of the main body, the first opening configured to receive at least one optical fiber through the back end of the main body; at least one optical fiber opening in communication with and extending from the first opening toward the front end, the at least one optical fiber opening configured to receive an optical fiber inserted through the back end, wherein the at least one optical fiber opening has a lens associated therewith, the lens having a convex surface that extends rearwardly from the front end towards the back end.
 13. The fiber optic ferrule according to claim 12, further comprising an optical fiber stop disposed within the at least one optical fiber opening.
 14. The fiber optic ferrule according to claim 12, further comprising a second opening disposed between the middle portion and the front end, the second opening extending through a surface of the main body perpendicular to a front face disposed at the front end of the main body and in communication with the at least one optical fiber opening.
 15. The fiber optic ferrule according to claim 14, further comprising a front portion, the front portion disposed between the second opening and the front end, the front portion having at least one lens hole, the at least one lens hole corresponding to the at least one optical fiber opening in the middle portion and opening into the second opening and having the lens disposed therein.
 16. The fiber optic ferrule according to claim 12, further comprising at least one mating surface disposed on the front face of the main body, the at least one mating surface corresponding to the at least one optical fiber receiving hole.
 17. The fiber optic ferrule according to claim 12, further comprising a mating surface, the mating surface corresponds to the front face of the fiber optic ferrule.
 18. The fiber optic ferrule according to claim 12, further comprising a plurality of light transmission surfaces, each of the plurality of light transmission surfaces being optically aligned with one of the plurality of lens holes and one of the plurality of optical fiber openings. 